The primary objective of this study is to produce Bauhinia monandra biodiesel (BMB) using seed waste and improve its energy and environmental properties by integrating a cetane enhancer. The methyl ester of biooil was obtained using the transesterification method, and the properties were analyzed. Different quantities of BMB were combined with diesel fuel, and 2-ethyl hexyl nitrate (EHN) was introduced to the blend of 30% BMB-diesel fuel to improve both energy and environmental performance measurements. The research findings indicate that the FAME and physicochemical properties of BMB are comparable to those of diesel fuel. The brake thermal efficiency (BTE) of the engine decreases by 4.2% for 30% BMB blended fuel, whereas hydrocarbon (HC), carbon monoxide (CO), and smoke emissions decrease by 11.6%, 6.7%, and 10.5%, respectively. As the concentration of BMB increases, there is a reduction in both the maximum value of in-cylinder pressure and the net heat release rate. Conversely, brake-specific fuel consumption (BSFC) and NOx emissions increase by 5.7% and 4.7%, respectively. The incorporation of EHN in the test fuel enhances BSFC and BTE by 4.2% and 4.3%, respectively, whereas NOx, HC, and CO emissions are reduced by 5.2%, 9.2%, and 9.9%, respectively.